We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we’ll assume that you are happy to receive all cookies from this website. If you would like to change your preferences you may do so by following these instructions.

Objective of the experiment: To understand on how different light intensities that sum up to equal DLI is effecting growth of lettuce. Earlier trials without far-red had showed similar results when aspect of crop production between the different ways to distribute the light over a day.

(This is a summary of the findings produced by the Heliospectra PlanLab. For full report please contact our lab or sales team.)

Place and duration: Heliospectra PlantLabSpecies: Lettuce – Black seeded SimpsonLamps: LX601CPAR: Varies to achieve DLI of 13.0Photoperiod: 16 hours (8.00-0.00)Results: The lettuce grown with far-red were larger and had higher biomass than lettuce grown without far-red.Objective of the experiment: To understand on how different light intensities that sum up to equal DLI is effecting growth of lettuce. Earlier trials without far-red had showed similar results when aspect of crop production between the different ways to distribute the light over a day.

METHOD

Lettuce, Black seeded Simpson, were sown (4 seeds per pot) and kept in the germination area under 24 hours light for 5 days. The pots were thinned out to 1 plant per pot and placed in growth units, a 1.4-m2 (15ft2) open area with reflective curtains with a LX601C.

The photoperiod for all units were 16 hours, 8.00 – 0.00. The room temperature set point was 22ºC/17ºC (day/night) and humidity set to 60 %.

The LX601C was used to set DLI light strategies in the experiment with the same spectrum within PAR. The light intensity varied over the day to simulate natural daylight intensities; lower morning and night while highest during mid-day. Two spectrums were tested. The first spectrum contained blue, red and white LEDs. The second day simulation contained additional far-red added to the spectrum with a constant on red: far-red. Both light treatments sum up to the same daily light integral, DLI = 13.

28 days into the experiment, 5 pots per unit containing 1 plant were collected and measured. Average plant height, head size and leaves were counted, and fresh weight taken with a scale.

RESULTS

The lettuce grown under a spectrum without far-red were smaller, more compact and darker green than with far-red. The visual difference between the treatments was that with far-red the lettuce were larger, looser and paler in color. A 13% increase in the diameter of the lettuce were recorded in comparison to lettuce treated with light containing no far-red. It also had a 43% increase in fresh biomass, compared to lettuce grown under the day simulation without far-red.

Picture. Simpson lettuce at harvest, 28 days of treatment, from left to right without and with FR. Gothenburg 31st of March 2016.